Method of manufacturing semiconductor device

ABSTRACT

In a method of manufacturing a capacitor, a semiconductor substrate is provided. On the semiconductor substrate, a transistor is formed. Then, a first conductive layer is formed on the substrate. An insulating layer is formed on the first conductive layer. A second conductive layer is formed on the insulating layer. The second conductive layer is patterned to form an upper electrode. Finally, the first conductive layer is patterned to form a lower electrode and a conductive pattern after the formation of the upper electrode.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of manufacturing a semiconductor device, and specifically to a method of manufacturing a semiconductor device, which enhances reliability of an insulating film upon formation of a capacitor and prevents penetration of contact holes on a capacitor electrode.

[0003] 2. Description of the Related Art

[0004] Enhancing reliability of an insulating film of a capacitor interposed between an upper electrode and a lower electrode is very important to a method of manufacturing a semiconductor device. In a method of manufacturing a semiconductor device including a conventional capacitor structure, a transistor is first formed on a wafer. A metal, which serves as a lower electrode of a capacitor, and an insulating film for the capacitor, which is formed of an Si oxide film or the like, are deposited over the transistor in this order.

[0005] The metal and the insulating film are patterned so as to form a lower electrode, and a capacitor metal is formed thereon. The capacitor metal is patterned to form an upper electrode. In order to make contact with the lower and upper electrodes, contact holes are defined in an interlayer film formed at their upper portions.

[0006] In the aforementioned conventional manufacturing method, the lower electrode is first patterned and thereafter the capacitor metal (CM) is deposited and etched to form the upper electrode. However, since a resist is directly applied onto the insulating film upon patterning of the lower electrode in the conventional manufacturing method, the resist is directly applied even to an area interposed between the upper and lower electrodes on the insulating film as a matter of course. Therefore, the film quality of the surface of the insulating film changes and is affected by an organic release agent or the like even upon removing the resist on the insulating film after the etching, thereby deteriorating the reliability of the insulating film.

[0007] If an etching-rate selection ratio is low when the contact holes are collectively made open on the lower and upper electrodes by etching, then there is a possibility that the upper electrode will be excessively etched due to the difference between their depths, and the contact holes will be defined through the upper electrode.

[0008] Further, when the organic release agent or the like for removing the resist infiltrates into edge portions of the upper electrode upon formation of the lower electrode by etching, this will influence the quality of the insulating film near the edge portions. Furthermore, a problem arises in that when the interlayer film is deposited by CVD or the like using plasma after the formation of the capacitor, the insulating film is damaged by the plasma of CVD and thereby brought into deterioration, whereby the reliability of the insulating film is reduced.

SUMMARY OF THE INVENTION

[0009] The present invention may provide a method of manufacturing a semiconductor device having a capacitor, wherein an insulating film is high in reliability.

[0010] In a method of manufacturing a capacitor of the present invention, a semiconductor substrate is provided. On the semiconductor substrate, a transistor is formed. Then, a first conductive layer is formed on the substrate. An insulating layer is formed on the first conductive layer. A second conductive layer is formed on the insulating layer. The second conductive layer is patterned to form an upper electrode. Finally, the first conductive layer is patterned to form a lower electrode and a conductive pattern after the formation of the upper electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

[0012] FIGS. 1(a) through 1(f) are respectively schematic cross-sectional views for describing process steps of a method of manufacturing a semiconductor device, according to a first embodiment;

[0013] FIGS. 2(a) through 2(g) are respectively schematic cross-sectional views for describing process steps of a method of manufacturing a semiconductor device, according to a second embodiment; and

[0014] FIGS. 3(a) through 3(c) are respectively schematic cross-sectional views for describing process steps of a method of manufacturing a semiconductor device, according to a third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

[0016] A first embodiment of the present invention, showing a method of manufacturing a semiconductor device will be explained. According to the method of manufacturing the semiconductor device of the first embodiment, a conductive layer is formed in accordance with the following procedures in a conductive layer forming process step subsequent to the formation of a transistor. The method of manufacturing the semiconductor device, according to the first embodiment will be described below using FIG. 1.

[0017] A transistor is first formed on a semiconductor substrate 100. Thereafter a capacitor lower electrode metal (2M) 101, an insulating film 102, and a capacitor upper electrode metal (CM) 103 are deposited on the semiconductor substrate 100 in this order as shown in FIG. 1(a). An Si oxide film or the like can be used as the insulating film 102.

[0018] Next, the surface of the upper electrode metal (CM) 103 is coated with a resist, and an unnecessary area is removed from the upper electrode metal (CM) 103 by etching and the metal (CM) 103 is patterned, thereby forming an upper electrode 104 on the insulating film 102 as shown in FIG. 1(b). Since, at this time, the insulating film 102 is interposed between the metal (CM) 103 and the metal (2M) 101, the resist is not directly applied onto its surface. Incidentally, the resist placed over the upper electrode 104 and the insulating film 102 is removed by an organic release agent or the like after the etching.

[0019] After the formation of the upper electrode 104, the metal (2M) 101 is etched to remove an unnecessary area and subjected to patterning, thereby forming a lower electrode 105. A capacitor 106 is formed of the upper electrode 104, insulating film 102 and lower electrode 105 as shown in FIG. 1(c) in this way. In the present embodiment, the metal (2M) 101 is patterned to form the lower electrode 105 and form a conductive metal 107 comprised of the metal (2M) 101 and the insulating film 102.

[0020] Thereafter, as shown in FIG. 1(d), an interlayer film 108 is deposited over the capacitor 106 and the conductive metal 107. Further, the surface of the interlayer film 108 is planarized by CMP or the like and thereafter contact holes 109 are formed on the upper electrode 104, lower electrode 105 and conductive metal 107 by batch or block etching as shown in FIG. 4(e). Incidentally, the deposition of the interlayer film 108 can be carried out by CVD or the like using plasma.

[0021] After the formation of the contact holes 109, a conductive metal (3M) is deposited on the interlayer film 108 and subjected to patterning to form conductive metals (3M) 110 as shown in FIG. 1(f), whereby a conductive layer is formed.

[0022] According to the semiconductor device manufacturing method of the present embodiment, since the upper electrode metal (CM) 103 and the lower electrode metal (2M) 101 are etched after the deposition of the upper electrode metal (CM) 103 on the insulating film 102, the insulating film 102 is covered with the upper electrode 104 upon etching of the metal (2M) and thereby not brought into direct contact with the resist, whereby deterioration in reliability of the insulating film can be prevented.

[0023] According to a method of manufacturing a semiconductor device of a second embodiment, an offset oxide film is formed over an upper electrode and an insulating film before the formation of a lower electrode of a capacitor in the conductive layer forming process step. The method of manufacturing the semiconductor device, according to the second embodiment will be described below using FIG. 2.

[0024] In the present embodiment, a transistor is formed on a semiconductor substrate 200. Thereafter a capacitor lower electrode metal (2M) 201, an insulating film 202 such as an Si oxide film or the like, and a capacitor upper electrode metal (CM) 203 are deposited on the semiconductor substrate 200 in this order as shown in FIG. 2(a).

[0025] Next, the surface of the upper electrode metal (CM) 203 is coated with a resist, and an unnecessary area is removed from the metal (CM) 203 by etching and the metal (CM) 203 is patterned to form an upper electrode 204 on the insulating film 202 as shown in FIG. 2(b). Since, at this time, the insulating film 202 is interposed between the metal (CM) 203 and the metal (2M) 201 in a manner similar to the first embodiment, the resist is not directly applied onto its surface. Further, the resist placed over the upper electrode 204 and the insulating film 202 is removed by an organic release agent or the like after the etching.

[0026] After the formation of the upper electrode 204, an offset oxide film 205 is deposited over the surfaces of the upper electrode 204 and the insulating film 202 as shown in FIG. 2(c). An Si oxide film or the like can be used as the offset oxide film 205 in a manner similar to the insulating film 202. After the deposition of the offset oxide film 205, the metal (2M) 201 is etched to remove an unnecessary area and then patterned as shown in FIG. 2(d) to form a lower electrode 206.

[0027] When the resist that remains upon etching of the metal (2M) 201, is removed, the exposed surfaces of the upper electrode 204 and the insulating film 202 are covered with the offset oxide film 205 on the whole. It is therefore possible to prevent the organic release agent or the like from being infiltrated into upper electrode edge portions 207.

[0028] Thus, a capacitor 208 comprised of the upper electrode 204, the insulating film 202 and the lower electrode 206 is formed as shown in FIG. 2(d). In the present embodiment, the metal (2M) 201 is patterned to form the lower electrode 206 and form a conductive metal 209 comprised of the metal (2M) 201, the insulating film 202 and the offset oxide film 205.

[0029] Thereafter, as shown in FIG. 2(e), an interlayer film 210 is deposited on the capacitor 208 and the conductive metal 209 by CVD using plasma. Further, the surface of the interlayer film 210 is planarized by CMP or the like. Since the insulating film 202 is covered with the offset oxide film 205 upon deposition of the interlayer film 210 by CVD using the plasma, damage produced due to the plasma can be reduced.

[0030] After the deposition of the interlayer film 210, contact holes 211 are formed on the upper electrode 204, the lower electrode 206 and the conductive metal 209 by block etching as shown in FIG. 2(f). Further, a conductive metal (3M) is deposited on the interlayer film 210 after the formation of the contact holes 211 and then patterned to form conductive metals (3M) 212 as shown in FIG. 2(g), whereby a conductive layer is formed.

[0031] According to the method of manufacturing the semiconductor device, according to the present embodiment, the offset oxide film is formed over the upper electrode and the insulating film before the formation of the lower electrode of the capacitor in the conductive layer forming process step. It is therefore possible to prevent the quality of the insulating film 202 near each upper electrode edge portion 207 from contacting the organic release agent or the like in addition to the prevention of a change in the film quality due to the direct contact of the resist to the insulating film 202 and to improve reliability of the insulating film 202. It is also possible to prevent deterioration of the insulating film 202 and a change in the quality thereof upon deposition of the interlayer film 210 by CVD and thereby improve reliability of the insulating film 202.

[0032] A method of manufacturing a semiconductor device of a third embodiment will be described using FIG. 3. Upon forming a conductive layer on a semiconductor substrate in a process similar to the second embodiment in the present embodiment, the insulating film and the offset film are formed of silicon oxide/nitride (SiON).

[0033] In the second embodiment, the whole surface of the insulating film 202 is covered with the offset oxide film 205 before the etching of the lower electrode metal (2M) 201. Therefore, the insulating film 202 near the upper electrode edge portions 207 is protected from infiltration of the organic release agent or the like upon etching of the metal (2M) 201.

[0034] Since an offset oxide film 302 formed of SiON is deposited on the surface of an insulating film 301 formed of SiON as shown in FIG. 3(a) in the present embodiment, it is capable of compensating for damage such as a reduction in the insulating film 301 which undergoes it upon forming the upper electrode 204.

[0035] Since the insulating film 301 and offset oxide film 302 both formed of SiON are low in etching rate as compared with the interlayer film 210, an etching-rate selection ratio between each of the insulating film 301 and offset oxide film 302 and the interlayer film 210 can be taken adequately.

[0036] Therefore, even when the contact holes 303 are collectively formed by etching, etching first proceeds to an interface between the interlayer film 210 and the offset oxide film as shown in FIG. 3(b) regardless of the depth as viewed from the surface of the interlayer film 210. Thereafter, as shown in FIG. 3(c), etching proceeds in order of the offset oxide film 302 and the insulating film 301 to define the contact holes 303. However, since the depths from the interface between the offset oxide film 302 and the interlayer film 210 to the surfaces of the upper electrode 204 and the lower electrode 206 substantially remain unchanged so far, the upper electrode 204 is not excessively etched.

[0037] According to the semiconductor device manufacturing method showing the present embodiment, the formation of the insulating film and the offset oxide film by using SiON makes it possible to reduce deterioration or the like in the quality of the insulating film due to etching upon formation of the upper electrode in addition to advantageous effects obtained in the first and second embodiments and to provide a further improvement in the reliability of the insulating film. Since the etching-rate selection ration between the interlayer film and the offset oxide film can be taken adequately, it is possible to prevent the contact holes from being defined through the upper electrode.

[0038] Incidentally, in the present invention, the known ones can be suitably selected within the scope not impairing the effect of the present invention, as respective conditions for photolithography including the etching for forming the upper and lower electrodes of the capacitor, etc., conditions for respective members, etc.

[0039] While the present invention has been described with reference to the illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to those skilled in the art on reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention. 

What is claimed is:
 1. A method of manufacturing a capacitor comprising: providing a semiconductor substrate on which a transistor is formed; forming a first conductive layer on the substrate; forming an insulating layer on the first conductive layer; forming a second conductive layer on the insulating layer; patterning the second conductive layer to form an upper electrode; and patterning the first conductive layer to form a lower electrode and a conductive pattern after the formation of the upper electrode.
 2. A method of manufacturing a capacitor according to claim 1, further comprising: forming an interlayer film on the upper and lower electrodes; forming a plurality of contact holes through the interlayer film and the insulating layer so as to expose the upper and lower electrodes and the conductive pattern; and forming a third conductive layer on the interlayer film and the contact holes.
 3. A method of manufacturing a capacitor according to claim 2, wherein the interlayer film is formed by a plasma CVD.
 4. A method of manufacturing a capacitor according to claim 1, wherein the patterning the second conductive layer including: forming a resist pattern formed on the second conductive layer; etching the second conductive layer using a resist pattern as a mask; and removing a resist layer.
 5. A method of manufacturing a capacitor according to claim 4, wherein the resist layer is removed by an organic release agent.
 6. A method of manufacturing a capacitor according to claim 1, wherein the insulating layer is substantially patterned with the first conductive layer simultaneously.
 7. A method of manufacturing a capacitor comprising: providing a semiconductor substrate on which a transistor is formed; forming a first conductive layer on the substrate; forming an insulating layer on the first conductive layer; forming a second conductive layer on the insulating layer; patterning the second conductive layer to form an upper electrode; forming an offset insulating layer on the upper electrode and the insulating layer; patterning the first conductive layer to form a lower electrode and a conductive pattern after the formation of the upper electrode.
 8. A method of manufacturing a capacitor according to claim 7, further comprising: forming an interlayer film on the offset insulating layer; forming a plurality of contact holes through the interlayer film, the offset insulating layer and the insulating layer so as to expose the upper and lower electrodes and the conductive pattern; and forming a third conductive layer on the interlayer film and the contact holes.
 9. A method of manufacturing a capacitor according to claim 8, wherein the interlayer film is formed by a plasma CVD.
 10. A method of manufacturing a capacitor according to claim 7, wherein the patterning the second conductive layer including: forming a resist pattern formed on the second conductive layer; etching the second conductive layer using a resist pattern as a mask; and removing a resist layer.
 11. A method of manufacturing a capacitor according to claim 10, wherein the resist layer is removed by an organic release agent.
 12. A method of manufacturing a capacitor according to claim 7, wherein the offset insulating layer and the insulating layer are substantially patterned with the first conductive layer simultaneously.
 13. A method of manufacturing a capacitor according to claim 7, wherein the offset insulating layer is formed of an oxide.
 14. A method of manufacturing a capacitor according to claim 7, wherein the offset insulating layer is formed of a silicon oxide/nitride.
 15. A method of manufacturing a capacitor comprising: providing a semiconductor substrate on which a transistor is formed; forming a first conductive layer on the substrate; forming a first silicon oxide/nitride layer on the first conductive layer; forming a second conductive layer on the first silicon oxide/nitride layer; patterning the second conductive layer to form an upper electrode; forming a second silicon oxide/nitride layer on the upper electrode and the insulating layer; patterning the first conductive layer to form a lower electrode and a conductive pattern after the formation of the upper electrode.
 16. A method of manufacturing a capacitor according to claim 15, further comprising: forming an interlayer film on the second silicon oxide/nitride layer; forming a plurality of contact holes through the interlayer film, the first and second silicon oxide/nitride layers so as to expose the upper and lower electrodes and the conductive pattern; and forming a third conductive layer on the interlayer film and the contact holes.
 17. A method of manufacturing a capacitor according to claim 16, wherein the interlayer film is formed by a plasma CVD.
 18. A method of manufacturing a capacitor according to claim 15, wherein the patterning the second conductive layer including: forming a resist pattern formed on the second conductive layer; etching the second conductive layer using a resist pattern as a mask; and removing a resist layer.
 19. A method of manufacturing a capacitor according to claim 18, wherein the resist layer is removed by an organic release agent.
 20. A method of manufacturing a capacitor according to claim 15, wherein the first and second silicon oxide/nitride layers are substantially patterned with the first conductive layer simultaneously. 